Method of performing signal reconstruction at the receiving end of a communications system, such as for GSM

Abstract

The invention provides a method of performing signal reconstruction at the receiving end of a communications system that uses a discrete channel estimate of the communications channel for the communications system. The discrete channel estimate is obtained from received discrete signal samples, which have N discrete channel tap components, where N is a positive integer. One method includes the steps of: reconstructing a first discrete signal using N of the discrete channel tap components of the discrete estimate of the communications channel; and reconstructing a second discrete signal using the first reconstructed discrete signal and one of the N discrete channel tap components. Another method includes the steps of: reconstructing a first discrete signal using N of the discrete channel tap components of the discrete estimate of the communications channel; and reconstructing a second discrete signal from the first reconstructed discrete signal by complementing the first reconstructed discrete signal. Further, a binary digital signal processing system for performing signal reconstruction at the receiving end of a communications system includes a binary digital signal processor, a memory unit, and a signal bus. The binary digital signal processor can reconstruct a second discrete signal from a first reconstructed discrete signal and one of N discrete channel components or by complementing the first reconstructed discrete signal.

The invention claimed is: 
     
       1. A method of performing signal reconstruction at the receiving end of a communications system using a discrete channel estimate of the communications channel for the communications system, the discrete estimate being obtained from received discrete signal samples and having N discrete channel tap components, where N is a positive integer, said method comprising the steps of: reconstructing a first discrete signal using N of the discrete channel tap components of the estimate of the communications channel; and   reconstructing a second discrete signal using the first reconstructed discrete signal and using one of the N discrete channel tap components.   
     
     
       2. The method of claim 1, and further comprising the step of: reconstructing a third discrete signal using a reconstructed discrete signal selected from the group of reconstructed discrete signals consisting essentially of said first reconstructed discrete signal and said second reconstructed discrete signal and using one other of the N discrete channel tap components.   
     
     
       3. The method of claim 2, and further comprising the step of: reconstructing a fourth discrete signal by complementing a discrete signal selected from the group of discrete signals consisting essentially of said first reconstructed discrete signal, said second reconstructed discrete signal, and said third reconstructed discrete signal.   
     
     
       4. The method of claim 1, wherein said first reconstructed discrete signal and said second reconstructed discrete signal each correspond to states of a signal modulation scheme employed to transmit binary digital signals from the transmitting end to the receiving end of a wireless communications system via the communications channel.   
     
     
       5. The method of claim 4, wherein the signal modulation scheme comprises minimum phase-shift keying (MSK) modulation.   
     
     
       6. The method of claim 1, wherein the discrete estimate of the communications channel is stored in a memory;   wherein the step of reconstructing a first discrete signal comprises:   reading N of the discrete channel tap components of the estimate of the communication channel from the memory; and   accumulating a superposition of the N discrete channel tap components using, for each discrete channel tap component, a discrete channel tap component selected from the group of discrete channel tap components consisting essentially of the discrete channel tap component and its complement.   
     
     
       7. The method of claim 6, where the superposition of the N discrete channel tap components is accumulated using an arithmetic logic unit (ALU). 
     
     
       8. The method of claim 6, wherein the superposition of the N discrete channel tap components is accumulated using a digital signal processor (DSP). 
     
     
       9. The method of claim 6, wherein the superposition of the N discrete channel tap components is accumulated by respectively accumulating the real and imaginary components of the N discrete channel tap components. 
     
     
       10. The method of claim 6, wherein the step of reconstructing a second discrete signal comprises: reading the one of the N discrete channel tap signal components from the memory; and   accumulating a superposition of the first reconstructed discrete signal and a discrete channel tap component selected from the group of discrete channel tap components consisting essentially of the one of the N discrete channel tap components, its complement, twice the one of the N discrete channel tap components, and twice its complement.   
     
     
       11. A method of performing signal reconstruction at the receiving end of a communications system using a discrete channel estimate of the communications channel for the communications system, the discrete estimate being obtained from received discrete signal samples and having N discrete channel tap components, where N is a positive integer, said method comprising the steps of: reconstructing a first discrete signal using N of the discrete channel tap components of the estimate of the communications channel; and   reconstructing a second discrete signal by complementing the first reconstructed discrete signal.   
     
     
       12. The method of claim 11, and further comprising the step of: reconstructing a third discrete signal using a reconstructed discrete signal selected from the group of reconstructed discrete signals consisting essentially of said first reconstructed discrete signal and said second reconstructed discrete signal and using one other of the N discrete channel tap components.   
     
     
       13. The method of claim 11, wherein said first reconstructed discrete signal and said second reconstructed discrete signal each correspond to states of a signal modulation scheme employed to transmit binary digital signals from the transmitting end to the receiving end of a wireless communications system via the communications channel.   
     
     
       14. The method of claim 13, wherein the signal modulation scheme comprises minimum phase-shift keying (MSK) modulation.   
     
     
       15. The method of claim 11, wherein the discrete estimate of the communications channel is stored in a memory;   wherein the step of reconstructing a first discrete signal comprises:   reading N of the discrete channel tap components of the estimate of the communication channel from the memory; and   accumulating a superposition of the N discrete channel tap components using, for each discrete channel tap component, a discrete channel tap component selected from the group of channel tap components consisting essentially of the discrete channel tap component and its complement.   
     
     
       16. The method of claim 15, wherein complementing the first reconstructed discrete signal is performed using an exclusive OR gate. 
     
     
       17. A binary digital signal processing system for performing signal reconstruction at the receiving end of a communications system, said system comprising: a binary digital signal processor;   a memory containing, stored in predetermined memory locations, a first reconstructed discrete signal and N discrete channel tap components of a discrete channel estimate of the communications system, N being a positive integer; and   a signal bus coupling said binary digital signal processor to said memory unit;   said binary digital signal processor being configured so as to reconstruct a second discrete signal from the first reconstructed discrete signal and one of the N discrete channel tap components.   
     
     
       18. The binary digital signal processing system of claim 17, wherein said binary digital signal processor is further configured so as to reconstruct a third discrete signal from the complement of the first reconstructed discrete signal. 
     
     
       19. A binary digital signal processing system for performing signal reconstruction at the receiving end of a communications system, said system comprising: a binary digital signal processor;   a memory containing, stored in predetermined memory locations, a first reconstructed discrete signal and N discrete channel tap components of a discrete channel estimate of the communications system, N being a positive integer; and   a signal bus coupling said binary digital signal processor to said memory unit;   said binary digital signal processor comprising means for reconstructing a second discrete signal from the first reconstructed discrete signal and one of the N discrete channel tap components.   
     
     
       20. The binary digital signal processing system of claim 19, wherein said binary digital signal processor further comprises means for reconstructing a third discrete signal from the complement of the first reconstructed discrete signal.